ECO REFERENCE MANUAL
12-7
EMC
ELECTRO-MAGNETIC
INTERFERENCE (EMI)
The inverters are designed to operate in an
environment where a high level of Electro-
Magnetic Interference (EMI) can be expected.
Usually, good installation practices will ensure
safe and trouble-free operation. If there are
any problems, the following guidelines may
prove useful. In particular, grounding of the
system at the inverter, as described below,
may prove effective. The figures at the end of
this section illustrate how filters should be
installed and connected.
• Ensure that all equipment in the cubicle is
well earthed using short, thick earthing
cable connected to a common star point or
busbar. It is particularly important that any
control equipment (such as a BMS), that is
connected to the inverter is also connected
to the same earth or star point as the
inverter via a short, thick link. Flat
conductors (e.g. braids or metal brackets)
are preferred as they have lower impedance
at high frequencies.
Connect the return earth from motors
controlled by the inverter directly to the
earth connection (PE) on the associated
inverter.
• On the MIDIMASTER Eco, use saw-tooth
washers when mounting the inverter and
ensure that a good electrical connection is
made between the heatsink and the back
panel, removing paint if necessary to
expose bare metal.
• Wherever possible, use screened leads for
connections to the control circuitry.
Terminate both the ends of the cable neatly,
ensuring that unscreened wires are as short
as possible. Use cable glands whenever
possible and earth both ends of the screen
on the control cable.
• Separate the control cables from the power
connections as much as possible, using
separate trunking, etc. If control and power
cables need to cross, arrange the cables so
that they cross at 90° if possible.
• Ensure that contactors in the cubicle are
suppressed, either with R-C suppressors for
AC contactors or ‘flywheel’ diodes for DC
contactors, fitted to the coils. Varistor
suppressors are also effective. This is
particularly important if the contactors are
controlled from the output relay on the
inverter.
• Use screened or armoured cables for the
motor connections and ground the screen
at both ends via the cable glands.
• If the drive is to be operated in an Electro-
magnetic noise-sensitive environment, the
RFI filter should be used to reduce the
conducted and radiated interference from
the inverter. For optimum performance,
there should be a good conductive bond
between filter and metal mounting plate.
On no account must safety regulations be
compromised when installing inverters!
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